Problem: Khan.scratchpad.disable(); For every level Michael completes in his favorite game, he earns $870$ points. Michael already has $160$ points in the game and wants to end up with at least $3900$ points before he goes to bed. What is the minimum number of complete levels that Michael needs to complete to reach his goal?
Solution: To solve this, let's set up an expression to show how many points Michael will have after each level. Number of points $=$ $ $ Levels completed $\times$ Points per level $+$ Starting points Since Michael wants to have at least $3900$ points before going to bed, we can set up an inequality. Number of points $\geq 3900$ Levels completed $\times$ Points per level $+$ Starting points $\geq 3900$ We are solving for the number of levels to be completed, so let the number of levels be represented by the variable $x$ We can now plug in: $x \cdot 870 + 160 \geq 3900$ $ x \cdot 870 \geq 3900 - 160 $ $ x \cdot 870 \geq 3740 $ $x \geq \dfrac{3740}{870} \approx 4.30$ Since Michael won't get points unless he completes the entire level, we round $4.30$ up to $5$ Michael must complete at least 5 levels.